Vinyl cyanide (CH2CHCN) in interstellar space: potential spectral lines for its detection

Abstract

Vinyl cyanide is a molecule having planar geometry with electric dipole moment components, μa=3.821D and μb=0.687D. Thus, a-type transitions are very strong as compared to b-type transitions, and are considered in this investigation. The rotational levels for a-type transitions, may be divided into two distinct groups: one group having odd values of ka and the other having even values of ka. Using the known values of rotational and centrifugal distortion constant along with the electric dipole moment μa, we have calculated energies of lower 120 rotational levels, having energy up to 92cm−1, for each group, and the probabilities for radiative transitions between the levels. These radiative transition probabilities in conjunction with the scaled values of collisional rate coefficients are used in the Sobolev Large Velocity Gradient analysis. Out of a large number of lines, we have selected the strongest ones. In the low lying levels, besides the 4 observed lines of CH2CHCN, we have discussed about 8 additional transitions, of which 2 showing the phenomenon of anomalous absorption and 6 showing emission feature are found. These lines may play important role for the search of vinyl cyanide in a cosmic object.

Keywords

• Astrophysics
• Radiative transfer
• ISM: molecules
• Vinyl cyanide
• Astrobiology